1. Field of the Invention
This invention relates to the production of partially fried, frozen potato strips, and more particularly to a process for producing frozen parfried potatoes adapted for reconstitution by any of a number of heating processes, such as deep frying and microwave oven heating.
With the advent of microwave ovens and their versatility in food preparation, it has become important in recent years to provide a means of reconstituting partially fried, frozen foods. It is obviously desirable to provide a food product, such as French fried potato strips, having the organoleptic appeal (including internal and external texture, flavor and final color) of "start-from-scratch" strips made at home or by well-known fast food chains selling "French fries."
A number of solutions have been proposed to improve the crispness and rigidity of parfried potatoes after finish frying. For example, surface treatments of potato strips with various agents including modified starches, gums, alginates, calcium salts, and the like have been prepared. Surface treatment results are successful to a limited degree and vary with the condition of the raw potatoes used. Other procedures have been disclosed in various U.S. patents. For instance, U.S. Pat. No. 3,397,993 discloses a process for producing frozen parfried potato strips, wherein the strips are first blanched to a translucent condition and then dried in hot air (150.degree.-350.degree. F.), thereby removing 20-30% moisture prior to parfrying and freezing. U.S. Pat. No. 3,649,305 discloses a process wherein the potato strips are dried in hot air (150-350.degree. F.) to remove approximately 10-30% moisture, after which the strips were blanched, parfried and frozen.
2. Description of the Prior Art
U.S. Pat. No. 4,254,153 discloses a process, wherein the potato strips are blanched and subjected to a two-stage drying procedure, in which the strips are first exposed to high velocity ambient air for a period sufficient to reduce their weight by about 8-15%. The strips are then dried in circulated heated air to further reduce the weight by an additional 8-15%. After drying, the strips are maintained in a quiescent state for a short period of time to permit equalization of moisture distribution, whereafter the strips are parfried, frozen and packaged.
Other related U.S. patents include Pat. No. 4,317,842 which discloses a process wherein the potatoes are washed, peeled, trimmed, sorted, cut, blanched in a conventional manner, and thereafter starch coated, oil soaked, parfried and frozen. The list of proposed solutions further includes U.S. Pat. No. 3,355,299 directed to a process providing a reconstituted French fried product including a series of six steps, two involving blanching prior to freezing, one comprising freezing, and three (the steps of reconstitution) involving preliminary frying, air cooling, and refrying. This procedure would appear to be directed to institutional preparation since the preliminary frying is done following freezing and storage of a potato product, which has been previously water blanched and oil blanched.
U.S. Pat. No. 4,256,777 discloses a process for preparing an unpeeled potato by cutting the potato into wedge-shaped pieces with a substantially triangular cross-section, cooking or blanching the pieces, parfrying, freezing and packaging. A process for controlling the color of pre-fried potato slices is disclosed in U.S. Pat. No. 3,934,046, wherein raw potato pieces are pre-fried in edible oil for a short period, then leached with water. The leached pieces may be further processed by finish frying or parfrying and refrigerating for distribution.
Potato pieces processed for microwave heat treatment are disclosed in U.S. Pat. No. 3,881,028, wherein the potato pieces are produced by first partially gelatinizing the starch in the pieces of potato without effecting a moisture loss greater than 3%. This is done by means of a microwave heat treatment prior to deep fat frying and heating the pieces to effect a dehydration thereof. The inventors claim the treated pieces to be shelf stable without refrigeration and the potatoes are rehydrated by soaking in water. U.S. Pat. No. 4,219,575 disclosed a complex sinusoidal strip surface configuration for a so-called crinkle cut product which is subjected to a prolonged parfrying step, thereby exhibiting increased crispness when reconstituted by microwave oven treating. U.S. Pat. No. 4,109,020 discloses combined parfrying and drying steps to reduce strip moisture content.
UK patent application GB 2,078,081A discloses a process for preparing frozen French fried potatoes for oven reheating, wherein the potatoes are cut into strips, and the strips blanched, thereafter immersed in oil having a temperature not greater than about 300.degree. F. for a period of time sufficient to attain an increase in solids contents of 3-6%. The strips are first parfried in oil at between 360.degree. F. and 375.degree. F. for a period of time sufficient to attain a moisture content between 60-70% and then removed from the hot oil and subjected to a flow of cool air. The strips are parfried again in oil at a temperature between 340.degree. F. and 375.degree. F. for a period of time sufficient to attain a moisture content of between 55 and 40%. The strips are then frozen for later reconstitution in a conventional oven. An earlier U.S. Pat. No. 2,597,065 disclosed a process for preparing and treating potatoes wherein the potatoes are subjected to a series of steps including conditioning for starch and sugar content, washing, peeling, cutting, blanching, partially drying and packaging for fresh consumption, or quick freezing and packaging. U.S. Pat. No. 3,397,993 disclosed a process, wherein fresh potatoes are peeled, trimmed, cut into elongate segments, blanched with steam to translucency, dehydrated internally and from the surface to a weight loss of up to about 35%, fried for a short time and then frozen prior to finish frying.
Two relatively recent patents disclose processes for preparing frozen potato strips for later reconstitution and finish frying. U.S. Pat. No. 4,632,838 issued to Lamb-Weston, Inc. disclosed a method for making French fried potato strips comprising the steps of peeling and cutting raw potatoes into strips, steaming the strips, drying in ambient air, parfrying, cooling in cold air, parfrying again and then freezing. A disclosed modification of this patented invention includes blanching, cooling in cold air, blanching again, drying in ambient air, parfrying in cold air, parfried and then freezing. U.S. Pat. No. 4,590,080 issued to J. R. Simplot Company discloses a process wherein raw potato strips are first blanched, parfried, promptly frozen, parfried again, directly from the frozen state, and then finally frozen for packaging, storage and later reconstitution and finish frying.